Liwu

MacBook Losing Battery Overnight With the Lid Closed: See What Woke It

Published · Liwu behavior checked against 2.12.0 ()

A sleeping MacBook is not switched off. It wakes briefly many times a night; the one we measured did so about four times an hour and still lost no more than 2 points by morning. When the lid stays closed and 10% or 20% is gone, the Mac's own power log shows what happened: when it went to sleep, how often it woke, the reason recorded for each wake, and the charge at each step. One Terminal command prints that log, with no extra software.

Verified: Apple documentation checked October 13, 2026. Terminal commands and log lines checked on one Apple silicon MacBook running macOS 26.7.1; Apple does not document the log's format, and it may differ on other versions. Liwu 2.12.0 behavior checked October 13, 2026.

What the log shows What it suggests Where to look next
A few brief wakes an hour and a point or two lost overnight Ordinary sleep Nowhere
No sleep entry at the time you closed the lid The Mac did not go to sleep What is preventing sleep
Far more than a few brief wakes an hour, most with the same reason Something keeps waking the Mac That reason

First, measure it

Note the charge when you close the lid and again when you open it, with the Mac unplugged the whole time. Divide the points lost by the hours.

We know of no figure from Apple for what a sleeping MacBook should use, so here is one data point, not a standard. On the MacBook we checked, nine sleeps of 7 to 14 hours with the lid closed, on battery, each cost between 0 and 2 percentage points. The Mac woke briefly about four times an hour throughout.

The reports that describe a problem look different. One thread on Apple's forum, joined by dozens of owners, opens with a MacBook Pro losing about 20% overnight with the lid closed, and a log showing brief wakes again and again.

Read the power log in Terminal

pmset -g log prints what the manual calls "a history of sleeps, wakes, and other power management events". It needs no password. The output runs to thousands of lines, so filter it.

When the Mac went to sleep and when it fully woke:

pmset -g log | grep -E "Clamshell Sleep|Idle Sleep|Software Sleep| Wake  "

There are two spaces after Wake. Two lines from one night look like this (shortened):

2026-10-11 19:58:30 +0800 Sleep  Entering Sleep state due to 'Clamshell Sleep' ... Using Batt (Charge:74%)
2026-10-12 10:17:40 +0800 Wake   Wake from Deep Idle ... lid ... Using BATT (Charge:72%)

"Clamshell" is the manual's word for the lid. Using Batt or Using AC is the power source at that moment, and Charge is the battery level. This sleep lasted 14 hours and cost 2 points.

If there is no sleep line near the time you closed the lid, the Mac stayed awake. Skip to "If the Mac never went to sleep".

Every brief wake in between:

pmset -g log | grep " DarkWake  "

The log's name for a brief wake is DarkWake. Use grep -c in place of grep to count them. A line looks like this:

2026-10-13 07:27:58 +0800 DarkWake  DarkWake from Deep Idle ... rtc/SleepService Using BATT (Charge:80%) 2 secs

The words between due to and Using are the reason; the table below covers the ones worth looking for. The number at the end is how long the wake lasted: on the Mac we checked, most took 2 seconds and the longest took 2 minutes.

What the reasons mean

Apple does not document these words, so read them with care.

In the log Reading How sure
lid, pwrbtn The lid was opened, the power button was pressed Plain from the name
USB-C_plug Something was plugged into a USB-C port Plain from the name
wifibt Wi-Fi or Bluetooth Plain from the name; the log does not say which
rtc/SleepService, rtc/Maintenance A timed wake the system scheduled for itself From the log's own "Wake Requests" lines

The last row made up nearly all brief wakes on the Mac we checked. To see which process asked for the next timed wake, and for when:

pmset -g log | grep "Wake Requests" | tail -3

On that Mac the requests came from three system processes: powerd, dasd, and mDNSResponder. At about four wakes an hour, it still lost no more than 2 points a night.

If the Mac never went to sleep

Something was holding it awake. While the Mac is in that state:

  • Run pmset -g. The sleep line names the processes that are preventing sleep: (sleep prevented by …). A line SleepDisabled 1 near the top means sleep has been switched off, lid included.
  • Run pmset -g assertions for the full list, with each process and the name it gave its request.
  • In Activity Monitor, open Energy and look at the Preventing Sleep column, which Apple describes as "whether this app is preventing your Mac from going to sleep".

A keep-awake tool that is still switched on does this on purpose. Liwu's own Keep Awake is one: with its scope set to Lid open + closed (a Pro option), it switches sleep off until the session ends. Apple also lists Spotlight indexing, apps that access a disk, and malfunctioning USB or Thunderbolt devices as things that keep a Mac from going to sleep.

What to change

These come from Apple's page on a Mac that sleeps or wakes unexpectedly. Change one thing per night so you can tell which one helped.

  1. Set Wake for network access to Never. System Settings → Battery → Options. Apple describes the setting as waking the Mac "to provide access to shared resources".
  2. Turn off sharing services you do not use. System Settings → General → Sharing.
  3. Disconnect USB and Thunderbolt devices, then reconnect them one at a time to find one that keeps the Mac awake.
  4. Update macOS, and if the drain continues, start in safe mode to see whether software that loads at startup is involved.

One more test comes from owners, not from Apple. In the forum thread above, owners report that the drain stopped once Bluetooth was off before the lid closed, and one adds that Wi-Fi made no difference. Nobody there established the cause. If your log is full of wifibt wakes, a night with Bluetooth off is a cheap test, not a fix.

If you need the charge in the morning whatever the cause, shut the Mac down or leave it on power.

What Liwu adds

Liwu reads the same log for you. This describes Liwu 2.12.0 on an Apple silicon MacBook running macOS 26.7.1; see compatibility for which Macs and macOS versions Liwu runs on.

In Liwu's main window, Battery Health has a Sleep section:

  • One row per sleep of 15 minutes or longer that began with the lid closing, inactivity, or a sleep command: when it began, how long it lasted, the charge before and after, and the number of brief wakes. The five most recent are listed, with a button to show all.
  • The reasons, counted. Open a row to see its brief wakes by reason, most frequent first, in plain words with the system's own word in brackets: "Wi-Fi or Bluetooth (wifibt)", "Scheduled system work (SleepService)". A reason Liwu does not recognize is shown as "Other" with the system's word.
  • A rate. A line above the list gives the number of sleeps and the average percentage per hour over the sleeps that ran on battery.
  • A mark on the costly ones. A sleep is marked "more than usual" when it ran on battery throughout, lasted at least two hours, and lost at least 5 points at 1 point an hour or more. A sleep that was on power for any part of it is marked "on power" instead, since its numbers do not show a cost.
  • A notification, if you want one. With Liwu's notifications turned on, a sleep marked "more than usual" produces one notification shortly after the Mac wakes: the points lost, the duration, the number of brief wakes, and the most frequent reason. It belongs to the Low battery kind in General → Notifications.

It is free, and the reading happens on your Mac.

What it does not do

  • It does not change how the Mac sleeps. It turns nothing off and prevents no wake. It is a report.
  • It goes back only as far as the system's log, about a week on the Mac we checked. Liwu keeps no history of its own.
  • It lists sleeps, not nights awake. A Mac that never went to sleep has no row; use the commands above for that case.
  • It does not interpret more than the log says. The plain words for timed wakes are our reading. When Liwu finds that it cannot understand the log, for example after a macOS update changes it, the section says so instead of showing an empty list.

FAQ

Is it normal for a MacBook to lose charge while asleep?

A little, yes. On the MacBook we checked, a night with the lid closed cost between 0 and 2 percentage points. Ten points or more overnight is worth a look at the log.

What is a DarkWake?

It is the power log's name for a brief wake during sleep. Apple's developer headers mention a "Dark Wake" state in which the processor and core hardware run instead of sleeping.

Do I need an app to find out what woke my Mac?

No. pmset -g log is part of macOS and shows everything this guide uses. An app saves you the filtering and the arithmetic.

Will Liwu stop the overnight drain?

No. It shows how much each sleep cost and what the log recorded as the reasons. The changes that can reduce drain are the macOS settings above.

Sources